Elena De Carolis, Mauro Nicoletti, Maria Assunta Casalino, Ersilia Fiscarelli, Gianni Prosseda, Raffaele Zarrilli, Angelo Iacobino, Bianca Colonna, Lucia Nencioni, Andrea Petrucca, Dipartimento Scienze Biomediche, Università degli studi 'G. d'Annunzio' Chieti-Pescara [Chieti-Pescara] (Ud'A), Dipartimento di Biologia, Università degli Studi Roma Tre, Department of Biology and Biotechnology 'Charles Darwin', Institut Pasteur, Fondation Cenci Bolognetti - Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Réseau International des Instituts Pasteur (RIIP)-Réseau International des Instituts Pasteur (RIIP)-Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome], U.O. Microbiologia, IRCCS Ospedale Pediatrico Bambino Gesù [Roma], Dipartimento di Scienze Mediche Preventive, Sezione di Igiene, Università degli studi di Napoli Federico II, Istituto di Microbiologia, Università cattolica del Sacro Cuore [Milano] (Unicatt), Department of Public Health and Infectious Diseases, Nicoletti, Mauro, Iacobino, Angelo, Prosseda, Gianni, Fiscarelli, Ersilia, Zarrilli, Raffaele, De Carolis, Elena, Petrucca, Andrea, Nencioni, Lucia, Colonna, Bianca, and Casalino, Maria Assunta
International audience; The genetic relatedness of 52 Stenotrophomonas maltophilia strains, collected from various environmental and clinical sources, including cystic fibrosis (CF) patients, as well as the presence and the expression of some virulence-associated genes were studied. Pulsed-field gel electrophoresis (PFGE) analysis identified 47 profiles and three clusters of isolates with an identical PFGE pattern considered to be indistinguishable strains. Restriction fragment length polymorphism of the gyrB gene grouped the 52 strains into nine different profiles. Most CF clinical isolates (29 out of 41) showed profile 1, while the analysis of the hypervariable regions of the 16S rRNA gene revealed five distinct allelic variations, with the majority of CF isolates (23 out of 41) belonging to sequence group 1. Furthermore, the strains were characterized for motility and expression of virulence-associated genes, including genes encoding type-1 fimbriae, proteases (StmPr1 and StmPr2) and esterase. All S. maltophilia strains exhibited a very broad range of swimming and twitching motility, while none showed swarming motility. A complete smf-1 gene was PCR-amplified only from clinically derived S. maltophilia strains. Finally, the virulence of representative S. maltophilia strains impaired in the expression of proteases and esterase activities was evaluated by infecting larvae of the wax moth Galleria mellonella. The results obtained strongly indicate that the major extracellular protease StmPr1 may be a relevant virulence factor of S. maltophilia.